This invention relates to a self-timer and its security device in a camera having a shutter priority automatic adjustment (EE) mode, a manual exposure adjustment mode or an aperture priority automatic exposure adjustment (ES) mode.
In the (EE) mode, a camera light passing through a lens aperture is reflected by the shutter top curtain while the lens aperture is being stopped down. The reflected light is received by a light receiving element and when a correct aperture value (the quantity of light) is obtained with respect to preset shutter speed (T.sub.V) and film sensitivity (S.sub.V) the supply of current to an aperture control magnet having attracted an aperture control lever is interrupted. The magnet is adapted to lock an operating member which is operated in association with the stopping-down operation, and when interrupted will stop the stopping-down operation thereby to determine an aperture value. The locking of the top curtain is at the same time released by the aperture control lever.
In the case where, even if the lens aperture is stopped down to its minimum aperture value and the correct aperture value (the quantity of light) cannot be obtained, it is impossible to deenergize the aperture control magnet without a variation in the quantity of light from the object. Therefore, in this case, the locking of the top curtain is not released, that is, the shutter is not operated. In addition, also in the (ES) operation of the manual operation in which no aperture control is carried out, the supply of current to the aperture control magnet is not interrupted, and therefore the shutter is not operated.
In order to overcome this difficulty, an interlocking timer circuit is provided and operates to interrupt the supply of current to the aperture control magnet in a period of time such that a period of time slightly longer than that required to stop down the full-aperture to the minimum aperture. This will then release the locking of the top curtain. In this connection, if after the shutter is released, the top curtain is opened to start the exposure with a delay time, the photographer may be unable to photograph the scene he wants at the proper time. Accordingly, it is suitable that the time of the interlocking timer is set to 100 ms at maximun, and 50-60 ms ordinary. If a change-over switch is provided in the circuit of the interlocking timer so that the time of the interlocking timer is set to approximately ten seconds, then the shutter is operated approximately ten seconds after the shutter is released. Therefore the interlocking timer can be used as a self-timer. Thus, an electrical self-timer can be readily obtained. However, in the (EE) mode of operation, simultaneously when the correct aperture value is obtained, the energization of the aperture control magnet is interrupted irrespective of the interlocking timer. As a result the aperture control is carried out and the locking of the top curtain is therefore released. Therefore, in this case, the interlocking timer cannot be used as the self-timer.